In a liquid crystal display (LCD), the liquid crystal panel itself does not emit light, thus requiring a separate backlight module to provide light for display. Edge-lit backlight module generally consists of parts such as light sources, reflectors, a light guide plate and a back plate.
In an edge-lit backlight module, light emitted from light sources at one side of the light guide plate directly enters into the light guide plate and travels to the opposite side of the light guide plate. When light strikes the surface of a diffusing point it bounces off in all directions and then exits the light guide plate from its light exiting surface. The light guide plate mainly functions to convert the incident light into planar light. The planar light from the light guide plate is then diffused and deflected, and finally gathered and adjusted in the direction normal to the display plane by two converging prism sheets having continuous zigzag-shaped groove surfaces.
Light emitting diode (LED) is commonly adopted as the light source in an edge-lit backlight module. Since a LED has a certain light emitting angle, fewer LEDs generally leads to uneven brightness at the light incident side, i.e., hot spots, and thus result in an uneven overall brightness of the backlight module.